Answer:
To lose weight in that area try doing cardio exercise and some exercises that tone the gluteus muscles. Hamstring curls would be helpful, as well as the superman pose, whick involves laying flat on your stomach, and raising the legs and arms off the ground, so that the only thing left touching the ground is the hips and mid section. Hold this pose for 30 seconds, then release. Also, try squats.
In addition, consuming fewer calories and refined (processed) carbohydrates can help in weight loss, throughout the body. Eat more 'fat burning' foods (see the related question and answer further down this page). As long as you are burning off, through such things as normal life and cardio exercise, more calories than you are consuming, you should experience weight loss.
If you have a tendency to gain weight in your rear end it will be the first place you will start losing weight when you exercise. Any form of cardio exercise, when done correctly, will work as long as you aren't eating excessive calories and refined (processed) carbohydrates.
For information about how to do cardio exercise correctly for fat burning, or for a list of refined (processed) carbohydrates, or to learn more about ''fat burning' foods, see the page links, further down this page, listed under Related Questions.